Vacuum tube shield and heat radiator



May 15, 1956 E. J. LIDEEN VACUUM TUBE SHIELD AND HEAT RADIATOR FiledJune 9, 1951 VACUUM TUBE SHIELD AND HEAT RADIATOR Ernest J. Lideen,Cicero, ill. Application June 9, 1951, Serial No. 23%,770 "7 (iiairns.(Cl. 174--35) This invention relates generally to vacuum tubes and moreparticularly to a combination radiation shield and heat radiator for usewith such tubes.

In radio and television receivers and transmitters it is frequentlyadvantageous to provide grounded shields to prevent interference betweencertain vacuum tubes and other components of the circuits. This isparticularly true when glass walled tubes are employed in the radiofrequency portions of the circuits.

Most vacuum tubes will operate more efficiently over long periods oftime if they are cooled so that they cannot become overheated, as islikely to occur when the eat developed by the tube filaments is notdissipated to the atmosphere at a high enough rate.

When conventional tube shields are employed to protect against radiationand stray fields the shields tend to decrease the rate of heat transferfrom the tube to the atmosphere, with a result that the tubes are evenmore likely to become overheated so that their effective life isshortened. I

Accordingly, one important object of this invention is to provide a tubeshield which increases rather than decreases in the rate at which heattransferred from the tube yet which completely encloses the tube toprevent electrical interference.

Another object is to provide a cylindrical element which may he slippedover a metal walled vacutun tube, where shielding is of littleimportance, and which will increase the rate of heat transfer from thetube so that the tube will operate at a lower temperature.

A further object is to provide the tube shield which forms a finnedradiator around the tube, having vertically disposed air ducts along thesides of the tube so that the tube may be cooled by conduction,radiation and convection.

hired States Patent 055cc A further object is a tube shield which alsomay be used as a shielding element or heat radiator or both forcondensers, whether dry or electrolytic, and other circuit elements, theshield also being adapted to enclose either circular or non-circularelements.

Another object is to provide a cylindrical shield which may be easilyfabricated from sheet material and whose diameter may be adjusted tosuit various sized tubes.

Other objects and advantages of the combination tube shield and radiatorof this invention will present themselves to those familiar with the arton reading the following specification in conjunction with the drawingsand appended claims.

In the drawing:

Fig. l is a perspective view of a glass walled vacuum tube provided withthe shield of this invention.

Fig. 2 is an elevation showing the manner in which the shield of thisinvention is used with a glass walled tube having straight sides, theshield being shown in section.

Fig. 3 is a view similar to Fig. 2, showing another form of the shieldinstalled on metal tube as a heat radiator.

2,745,395 Patented May 15, 1956 Fig. 4 is a view similar to Fig. 2,showing shield of this invention installed on a peanut tube.

Fig. 5 is a view similar to Fig. 4, showing a modified form of theshield having a cover and mounted on a grounding ring.

Fig. 6 is a plan view of a portion of a strip of metal which has beensevered longitudinally prior to corrugafrom.

Fig. 7 is a plan view of a portion of half the strip of Fig. 6 aftercorrugation, and

Fig. 8 is a perspective view showing a corrugated blank, bent to acylindrical shape, for installation on a vacuum tube.

A fundamental concept of the vacuum tube cooler and shield of thisinvention is to provide a longitudinally corrugated piece of sheetmetal, which is bent to a cylindrical shape about a longitudinal axisand slipped over a vacuum tube. The bottom edge of the corrugatedcylinder is provided with an irregular contour so to to provide aplurality of inlet ports at the bottom of the shield so that cool airmay enter near the base of the tube and flow upwardly through the spacedefined by the corrugations and over the surface of the tube to coolboth the tube and the shield.

In the detailed description which follows and in the claims, the wordshield is used to describe the cylindrical corrugated strip, regardlessof whether its primary purpose is to prevent electrical interference orsimply to facilitate the transfer of the dissipation of heat.

In Fig. l of the drawing a preferred embodiment of the shield 10 isshown installed on a glass-walled vacuum tube 11. The tube 11 is of thetype having generally upwardly diverging side walls, and the upperportion of the tube is larger than the base. Accordingly the shield 10is preferably supported on a grounding ring (shown in broken lines)which is fixed to the metal chassis 13.

The shield 10 is formed of a substantially rectangular piece of sheetmetal, preferably thin aluminum, which is corrugated and bent to acylindrical shape. The ends of the sheet indicated at 14 and 15 areslipped over one another so that the corrugations interlock as shown. Ifdesired the ends may be riveted or otherwise fastened together, but thisis not necessary or desirable in most cases. The bottom of the sheetwhich forms the shield 10, is cut to have a scalloped edge in order toprovide a plurality of air inlet openings 16, thus each of the flutes 17formed inside the shield 10 by the corrugations is open to theatmosphere outside of the grounding ring 12, near the base of the tube.This allows air to flow into the shield 10, up the flutes 17, over thetube 11 and out of the top end of the shield as indicated by the arrows18, and both the tube and the shield are continually cooled by a risingcolumn of air.

The inside of the shield 10 contacts the glass wall of the tube 11 nearthe top of the tube and, accordingly, heat is transferred by conductionfrom the tube to the shield. Similarly heat is transferred directly byradiation from the various parts of the tube to the shield. The shield10, of course, is also cooled on the outside by convection and radiationin addition to the cooling effect to the air flowing upwardly throughthe flutes it. In some cases it has proved desirable to employ acylindrical sleeve around the outer surface of the shield 30, in orderto provide exterior ducts to promote air circulation over the outside ofthe shield 10. In most instances, however, the construction shown isadequate.

The natural resiliency of the corrugated shield 16 causes it to engagethe sidewall of the tube 11 and the locking ring securely and also makessome variation in size possible, since the shield may be stretched toslip over tubes or rings which are somewhat larger than the normaldiameter of the shield. Similarly the engaging edges 14 and 15 maybedisengaged and made to overlap one or more additional corrugations toincrease or decrease diameter of the shield 10, thus a given shield maybe used with tubes of many difierent sizes, making it unnecessarytomanufacture and stock large'numbers of shields. The resiliency of thesidewall also makes it possible to use the shield, 10 on non-circularcylindrical. or prismatic objects since the shield tends to. follow the,shortest periphery when stretched over an object. This makes it possibleto use the shield 10, on most types of circuit components includingcondensers.

In Fig. 2, a shield 10 is shown installed on a-tube 111: havingcylindrical sidewalls. In this. installation no grounding ring is used,thefluted. ends of the, shield merely resting on the chassis 13 togroundthe shield. In this installation the fluted sides of the shield11) engage substantial portions of the tube wall to eflfect heattransfer by conduction from the tube to the shield. The lower end of theshield N is scalloped to provide air inlet ports 1% and engages the tubesocket 20.

The manner in which the shield of this inventionmay be used as a coolerfor a metal tube 11b is shown in Fig. 3. in this case the function ofthe shield 18 is primarily to cool the tube 11b, and, accordingly, theshield is slipped directly over the metal shell of the tube and, is notseparately grounded. The shield 1% contacts the walls of the tube 111;along its entire length to eflect very good conductive heat transferfrom the metal of the tube to the shield. The internal flutes 17b form aplurality of chimneys or ducts about the side of the. tube through whichcool air flows by convection, the chimney eifect substantiallyincreasing the rate of heat transfer over that which would occur if thetube were merely exposed to static air. The shield 10b differs from thepreferred embodiment in that both its upper and lower ends arescalloped. Otherwise it is identical, the scalloping of the upper endserving no function when the top of the tube is not covered. Thescalloped upper end results when a number of narrow strips are cut froma wide strip to form the blanks from which the shields are formed. Thiswill be clarified in the description of Figs. 68 which follows:

In Fig. 4 a smaller sized shield 10c is shown installed on peanut orbaseless type tube 110. This embodiment, except for size, issubstantially identical with that shown in Figs. 1 and 2.

In Fig. 5 a peanut tube 1111 is provided with a grounding ring 12!;surrounding, the socket Ztld and a two-piece shield i012 whichcompletely encloses the tube. The side portion of the shield, 10b isidentical with the shield ltlc, the shield; being stretched somewhat tofit over the grounding ring 1%. Toenclose the top of the' tube 11d a cupshaped cap 21 is provided. Thiscap has preferably the same diameter, asthe ring 121;, and it is slipped inside the shield 1% so as to leave theupper ends of the flutes 17b open to the atmosphere, thus thecirculation of air through the flutes and over the tube is not impededby the cap 21., To prevent the accumulation of heated air about thetube, an opening 22 is .provided in the center of cap 21. This openingalso permits the tube to be readily inspected to see whether thefilament is glowing.

Although a number of adaptations of, the shield of this invention havebeen shown, the examples are not exhaustive and other modifications orcombinations of the diflerent adaptations may be made in order to meetparticular situations. For example, the. shield of Fig. 1 may beprovided with a cap similar to the cap 21 should it prove desirable toshield the top of the tube 11. If the tube to be shielded is of the typewhich has a connection terminal on the top, a larger opening 22 or otherconventional arrangement would have to be provided in the cap 21 so thatthe lead wire to the top terminal would not touch the cap 21.

In some instances it, has. proved desirable. to use. a.

modified form of corrugation wherein the wave form is square orrectangular instead of sinusoidal. This produces somewhat betterconductive heat transfer because of the larger area of contact.

A preferred method of making the corrugated shields of this invention isshown in Fig. 6-8. The first step in this method is to sever anelongated strip of sheet metal into two halves along a sinusoidal lineas indicated at 24. This cut' 24 serves to form the scalloped edge whichforms the inlet ports 16 after the strips have been corrugated. The nextstep of the process is to take either half of the. longitudinallysevered strip and pass it through corrugating rolls to give it the shapeshown in Fig. 7. It is preferred that the scallops formed by the cut 24be in register with the corrugations so that when the shield is formedeach of the internal flutes 17 is provided with a port 18 at its lowerend. However, registration between the scallops and the flutes is notnecessary, and, if the period of the sinusoidal variation of thescalloped edge is different from the period of the sinusoidalcorrugation, random spacing will result with the further result that thebottoms of the flutes 17 will be sufiiciently open to. permit free airflow.

In Fig. 8, a corrugated strip is shown after having been cut to lengthand bent to form a cylinder. The step of cutting the strips to lengthmay be performed before the corrugation step, if desired, and when thisis done the corrugated rollers can be so arranged to bend the strip intoa cylinder during corrugation.

From the foregoing, it will be apparent that a superior shield has beenprovided, which not only encloses the circuit element to be shielded butalso promotes the cooling thereof and is useful as a cooling elementeven when shielding is not required, moreover, the device of thisinvention is universal in size so as to accommodate tubes or elements ofdifferent diameters and shapes and is inexpensively and easilyfabricated.

Various other changes or modifications in addition to those set forthherein and such as will present themselves to those familiar to the artmay be made without departing from the spirit of this invention thescope of which is commensurate with the following claims.

What is claimed is:

1. In combination a vacuum tube mounted in a tube socket, a groundingring surrounding said socket, and a tube shield supported uponsaid'grornding ring in slid able, telescoping relationship therewith andenclosing the sides of said tube, said shield comprising a corrugatedpiece of sheet metal affording vertical air flow channels and bent to acylindrical form having an internal diameter substantially the same assaid tube, the bottom of said shield having an irregular edge to provideair inlet openings sidewardly into the air flow channels formed by thecorrugations adjacent to said grounding ring.

2. A combination wave shield and heat dissipating accessory slidablyreceived on thermionic valves which comprises a cylindrical jacketconstructed of circumferentially undulating springable sheet metalcoextensive longitudinally with the envelope of a valve and formingalternate inner and outer longitudinally disposed flutes, the innerflutes having tangential contact with the periphery of the valveenvelope and the spaces intervening the flutes forming vertical chimneyflues stimulated by the radiant and convected heat emanating tom thevalve, and means for increasing the accessibility for replacement air tosaid flues comprising a lowermost skirting portion of said jacketscalloped at coincidence with said undulations.

3. In combination a vacuum tube mounted in a tube socket,, a groundingring surrounding said socket, and a tube shield supported upon saidgrounding ring in slidabletelescoping relationship therewith andenclosing the sides of said tube, said shield comprising a corrugated.piece ofsheet metal bent toform a cylinder having an internal diametersubstantially the same as the maximum diameter of said tube, the bottomof said shield having an irregular edge to provide air inlet openingssidewardly into the internal flutes formed by the corrugations adjacentto said grounding ring, and a cup shaped cap shield having a flange ofapproximately the same diameter as the ring received in readilyremovable sliding relationship within the upper end of the shield toleave the upper ends of the flutes open to the atmosphere, said internalflutes providing air flow chimneys Whose upper inner walls are definedby said cap.

4. The combination called for in claim 3 in which the cup shaped captelescopes in sliding relationship to a depth in the shield limited onlyby the tube itself to leave the top of said flutes open and unobstructedin a vertical direction.

5. A readily installed and removable radiation shield slidably receivedupon an electron discharge tube comprising a corrugated sheet metalmember of. high heat conductivity bent to a cylindrical form with edgesoverlapping difierent distances to afford difierent inside diameters,said corrugations extending longitudinally of said member to encompassand contact the tube along the inner folds of the corrugations toprovide intermediate vertically disposed air passageways defined byprotuberant flutes, said sheet metal corrugations being of springablestock permitting expansion of the shield to accommodate a range ofvariations in tube dimensions, the heat of said tube inducing convectiveflow of air through said passageways in direct contact with the tube,and means for increasing the intake capacity through said passagewayscomprising inclined cutaway portions at the lower ends of saidcorrugations affording lateral intake of air to said passageways.

6. A radiation shield slidably received upon an electron discharge tubewhich comprises an encircling jacket of corrugated sheet metal formed topresent alternate and opposite flute formations of sinusoidalcross-section, the sheet metal of said shield jacket being of thinflexible stock whereby to afford garter-like stretching to accommodatefor variations of tube envelope circumferences while permitting achimney forming engagement of the internal flute formations in heatexchange contact against the tube periphery along the entire tubelength, and a top closure for said shield comprising a plug formedcylinder cap with sides proportioned to have telescoping engagement withsaid flute formations at one end of said shield bottom of said shieldhaving an irregular edge to provide air inlet openings sidewardly intothe internal flute formations formed by the corrugations.

7. In combination a vacuum tube mounted in a tube socket, a groundingring surrounding said socket, and a tube shield supported upon saidgrounding ring in slidable telescoping relationship therewith andenclosing the sides of said tube, said shield comprising a corrugatedpiece of sheet metal bent to form a cylinder having an internal diametersubstantially the same as the maximum diameter of said tube, the bottomof said shield having an irregular edge to provide air inlet openingsinto the internal flutes formed by the corrugations adjacent to saidgrounding ring, and a cup shaped cap shield having a flange ofapproximately the same diameter as the ring received in readilyremovable sliding relationship within the upper end of the shield toleave the upper ends of the flutes open to the atmosphere, said shieldhaving overlapping interlocking nesting edges capable of engagement in aplurality of diflFerent relationships to provide a shield of differentdiameter.

References Cited in the file of this patent UNITED STATES PATENTS1,206,260 Schaanning et al Nov. 28, 1906 1,568,727 Frank Jan. 5, 19262,080,913 Hafecost et a1 May 18, 1937 2,250,647 Miller July 29, 19412,432,513 Depew Dec. 16, 1947

